Substituted amino alcohols



2,878,264". sussrrrurrnn AMINO :ALconoLs ,Carl Lnnsford, Richmond, Ya assignor to H. I Robins Company, Inc., Richmond, Va., a corporation or Virginia 'No Drawing.

Application September 26, 1957 Serial No.68 6,299

This invention relates to 3.-aryl derivatives of 3-pyrj rolidinol and is more particularly concerned with 3-aryl derivatives of N-hydrocarbon substituted-B-pyrrolidinols I and their acid addition salts.

The compounds of the present inventionare substituted pyrrolidinols and arerelated in action to such adrenergic blocking agents as N,N-dibenzyl-p-chloroethylamine (Dibenamine) and phenoxybenzamine (Dibenzyline).

The prior art with which the present compounds may Par nts rolidinols by substitution of an aryl, radical on the carbon atom at the 3 position.

Therefore, it is an object of this. invention to provide novel 3aryl-3pyrrolidinols. These compounds are characterized by single aryl and hydroxy substituents on the carbon atoms of the heterocyclic ring.

It is a further object of thisinvention to provide novel 3-aryl-3-pyrrolidinols wherein the l or N position is substituted by a hydrocarbon radical.

It is a special object of this invention to provide novel compounds which have an efiecton the circulatory system andwhich function as adrenergic blocking agents.

Members of this group of compounds by preliminary pharmacological tests have been shown to have utility as adrenergic blocking agents and as agents affecting the circulatory system.. i 1

This inventioncomprisesa novel group of 3-aryl derivatives of 3-pyrrolidinols, especially N hydrocarbon radical substituted-3-pyrrolidinols. The aryl substituent at the 3 position as defined in this specification and claims may be a simple aryl, such as phenyl, or a substituted aryl, such as an alkoxyor hydroxyor halogen-substituted aryl. Preferably the nitrogen atom in the pyrrolidine ring is substituted with a hydrocarbon radical, such as alkyl, aryl, aralky l' and the like. For solubility and other reasons, the acid addition salts such as the hydrohalides .are a preferred form of the invention.

Among the 3-aryl-3-pyrrolidinols operable within the scopeof the present invention arethe l-hyd-rocarbon radical substituted 3.-p-anisyl-3-pyrrolidinols, the vl-hydrocarsubstitnent.

2,878,264 e seg M 1 17, 1959 ",ice

- 3 pyrrolidinol hydrochloride; 1 ethyl 3 p hydroxyphenyl 3 pyrrolidinol and 3 phenyl 3 pyrrolidinol hydrochloride.

The compounds of the present invention may be ex- .pressed generally by the following formula:

where R is hydrogen or a hydrocarbon radical such as alkyl,

Preferred compounds within the scope of the present invention are the 3-phenyl-3-pyrrolidinols where the Nor 1 position is unsubstituted or substituted by a lower alkyl radical. Such compounds are exemplified by 3-phenyl-3- pyrrolidinol and 1-isobutyl-3rphenyl-3-pyrrolidinol.

Generally, the 3-aryl-3-pyrrolidinols are conveniently prepared by reaction of an N-substituted-3-pyrrolidinone in ethereal solution with a Grignard reagent whose corresponding aryl fraction is selected to introduce the 3-aryl Upon subsequent hydrolysis with an aqueous alkaline solution such as 50 percent sodium hydroxide, extracting with ether and recovering the ether extract, the free base is prepared usually in the form of an oil. The hydrohalide salts may be prepared from the base by an addition reaction in ethereal solution. The hydrohalide salts such as the hydrochloride addition salts are generally white powders. Both the free bases and the acid addition saltswere prepared. The salts were generally pre ferred for solubility and other reasons.

Compounds of this invention, when the N or 1 position are unsubstituted or contain-hydrogen may be conveniently prepared by catalytic hydrogenation of the corresponding l-benzyl compound. For example, in the presence of a 10 percent palladium catalyst on carbon, l-benzyl-3- phenyl-B-pyrrolidinol is converted to 3-phenyl-3-pyrthe art andrnay be prepared by a variation of the Dieckmann acetoacetic ester cyclization reaction adapted for nitrogen h'eterocycles according to the method of Prill and McElvain (J. A. C. S. 55, 1233 (1933) and also Leonard et al., J. A. C. S. 73, 2371 (1951) who describe the preparation of the N-methyl and .N- butyl members).

An example of the preparation of the pyrrolidinone starting material typical of the group is set out below.

3 PREPARATION I.l-ISOPROPYL-3- 'PYRROLIDINONE Ethyl ,8 isopropylaminopropionate.--Ethyl acrylate (1500 grams, moles) which was stabilized by the addition of 15 grams of hydroquinone was added at a rapid dropwise rate to 1182 grams moles) of isopropyl amine with stirring and control of the temperature at C. After complete addition the mixture was heated for four hours 'at C. and fractionated. The product 2220 grams (93 percent) was collected at 92 C./ 18

Ethyl e (N carbethoxymethyl N-isopropylamino) propionate.-A mixture of 1110 grams (7.0 moles) of ethyl -;3 -isopropylaminopropionate and 970 grams (7.0 moles) of anhydrous potassium carbonate was stirred and heated to C. under anhydrous conditions. While maintaining this temperature, 860 grams (7.0 moles) of ethyl chloroacetate was added dropwise with continuous stirring. After complete addition, heating at 100 C. was continued for four hours. The mixture was then cooled; one liter of cold water was added; and the oil layer was separated. The aqueous layer was extracted with ether which was combined with the oil,

dried over sodium sulfate, and fractionated. The product, 1112 grams (65 percent) boiled at 124-130 C./2.0 mm.

1-isopropyl-5-pyrrolidin0ne.-Anhydrous benzene (500 ml.) was added to a solution of 72.5 grams (3.15 moles) of sodium in 1500 ml. of dry methanol under anhydrous conditions To this refluxing solution was added 772 grams (3.15 moles) of ethyl-fi-(N-carbethoxymethyl-N- isopropylamino)-propionate in a steady stream and the mixture was stirred and partially distilled for one hour. A solution of 523 ml. (6.3 moles) of hydrochloric acid in one liter of water was added and the mixture was stirred and refluxed for three hours and then cooled to 20 C. Anhydrous potassium carbonate (434 grams, 3.15 moles) was added and the mixture was stirred for 20 minutes, filtered and extracted with about one liter of chloroform in several portions. The chloroform layer was dried over sodium sulfate and concentrated. Fractionation of the residue gave 213 grams (53 percent) of 1-isopropyl-3-pyrrolidinone boiling at 76 -80 C./ 20 mm.

The following examples illustrate the preparation of the 3-aryl-3-pyrrolidinols and their hydrohalide addition salts.

Example 1 .1-benzyl-3-phenyl-3-pyrrolidinol for one hour and hydrolysis was accomplished with water and 50 percent sodium hydroxide. The ether layer was 'decanted and the gummy residue was repeatedly extracted with ether.' The ether extracts were combined, washed with water, dried over sodium sulfate, and concentrated. Fractionation of the residue yielded 78 grams (61 per- .cent) of 1-benzyl-3-phenyl-3-pyrrolidinol as an oil, B. P.

169 -174 -C./0.2 mm.

The hydrochloride was prepared by precipitation of thesalt from an ethereal solution of the base by ethereal hydrogen chloride. After multiple crystallizations from butanone the melting point was 154156 C. The resulting compound, 1-benzy1-3-phenyl-3-pyrrolidinol hydroc'hloride was a white powder, soluble in water.

The 1-rnethyl-, 1-ethyl-, 1-n-propyl-, and l-isobutyl-S- phenyl-S-pyrrolidinols as free bases were prepared in an analogous manner and converted to hydrochloride addi tion salts. A summary of the properties ofthe ultimate compoundsds-set-out in TabIe I.

Example 2.-1-n-butyl-3-phenyl-3-pyrrelidinol In an apparatus protected from the atmosphere by a calcium chloride drying tube, a Grignard reagent, phenyl magnesium bromide, was prepared in the usual manner from 145 grams (0.93 mole) of bromobenzene and 22.6 grams (0.93 mole) of magnesium turning-s in about one liter of dry ether. To this solution there was added 65.5 grams (0.455 mole) of 1-n-butyl-3-pyrrolidinone, with stirring at a rate which maintained gentle reflux of the solution. After complete addition, stirring and refluxing was, continued for one hour and hydrolysis was accomplished with water and 50 percent sodium hydroxide. The ether layer was decanted and the gummy residue was re peatedly extracted with ether. The ether extracts were combined, washed with water, "and dried over sodium sulfate and concentrated. Fractionation of the residue yielded 41.5 grams (41.7 percent) of 1-n-butyl-3-phenyl- 3-pyrrolidinol, boiling point 134145 C./0.3 mm. In appearance the compound was a yellow oil.

The base was converted to the hydrochloride by solution in dry ether and the addition of ethereal hydrogen chloride. The oil which precipitated was crystallized from butanone and had afinal melting point of 118.5 C. The resulting compound, :1-n-butyl-3-phenyl-3- pyrrolidinol hydrochloride was a white powder, soluble in water.

Example 3.--3-p7znyl-3-pyrrolidin0l A solution of 78 grams (0.31 mole) of 1-benzyl-3- phenyl-3-pyrrolidinol in 200 ml. of absolute alcohol was shaken with 5 grams of 10 percent palladium on charcoal catalyst at 60 C. in an atmosphere of hydrogen until the theoretical amount of gas had been absorbed. About five hours were required. The solution was clarified'by filtration and concentrated, and the residue was fractionated. Yield 33.5 grams ('66 percent) of 3-phenyl-3-pyrrolidinol; B. P. 120-125 C./0.3 mm. After crystallization from toluene the melting point was 89-90 C.

Analysis-Calculated for C H NO: C, 73.59; H, 8.03. Found: C, 73.75; H,.8.03.

The hydrochloride was formed by precipitation from an ethereal solution of the base with ethereal hydrogen chloride. Recrystallization from isopropyl alcohol, a butanone-methanol mixture, or an absolute alcohol-ether mixture gave a constantmelting point of -1465 C. The 3-phenyl-3-pyrrolidinol hydrochloride produced was a white powder, soluble in water.

Example 4.1-methyI-3-p-meth0xyphenyl-3-pyrr0lidinol In an apparatus protected from the atmosphere by a calcium chloride drying tube a Grignard reagent, p-methoxyphenyl magnesium bromide, was prepared inthe'usual manner from 100 grams (0.535 mole) of p-bromoanisole and 13 grams (0.535 mole) of magnesium writings in about 500 ml. of dry ether. To this solution therew'ere added 25.8 grams (0.26 mole) of 1-methyl-3-pyrrolidinone with stirring at a rate which maintained gentle reflux of the solution. After complete addition, stirring and refluxing was continued for one hour, and hydrolysis was accomplished with water and 50 percent sodium hydroxide. The other layer was decanted and the gummy over sodium sulfate and concentrated. The residue was v pyrroll'dirwl 1 bromide, was prepared in"'theusual manner from 76.6 In an appa atus consistingof atwo liter three-neck gm-ms h pb and round-bottom flask fitted with. a mechanical stirrer, 2. grams 0' mole) mmmgsin about 300 dropping funnel and a calcium chloride protector con- 19 9 y Ff Q m? Y F .grams denscnthe .Grignard reagent, 2,2-dimethylbe1izodi (0.3 mole) of I-n-butyl-B -pyrrohdrone -w1th stirrmg at Iane-S-inagnesium bromide, [was 51505155101115 usual manner from 95 grams 0.42 111515 er's-bren're-zz .43" h*i 9 8E refluxmg were dimethylbenzodioxolane and 11 grams (0.44 mole) of i for i was hydrolyzed [magnesiumin about 500 ml. ofdryether. To this soluwith water and 50% aqueous sodmm hydFPxlde' The tion was added 28.2 grams (0.25 mole) of freshly 'disetherlayerwas and theigpmmy F was tilled 1-ethyl-3-pyrr01idinone with stirring at a rate which peatedly extracted ether" T h ether maintainedgentle reflux. After complete addition, the a were exttactedjvlth. and the mixture wasstir red for fifteen minutes and hydrolyzed a x was Paslfied Potassium I with waterand 50% aqueous sodium hydroxide. The 3 qx h r- T extmct was washed ether y r was Separated and the aqueous layer was with water, drredrover sodium sulfate and concentrated. tracted with several additional portions of ether. The h ,was e m m vacuo and 15 grams combined ether extracts were washed with water, dried (15%) i '011; B-' 57 i 03 was verted tothe hydro'chloridesalt by treating an ethereal fractionated at reduced pressure. The fraction boiling at 2o solutiOn withthel'fial y o t Th5 salt, which 130-1501? c./0.s nim was'obtained. This was tfriturated precipitatedes 11 1 crystallized f butan'one; with cc. of 10%'aqueous hydrogen chloride and filtered. The filtrate was heatedon the steam bath for 1 Analysislcalculated"fcr C1'1 12-22% fifteen minutes, cooled, extracted with ether, andfbasi- (31-; C. 57.93; H, Found'z l 2a22% Cl-; C, 57.84;

tied with solid sodium bicarbonate whichcausedprecipi- 25 7-27? tation of the solid product. g i Members of this group of compounds have been tested I r malyslmper eent Foundmercent Yield 1110.150 .R. R X" Solu- .'Mol.. Melting Calculated For- 1 1 1 (per- LV. 1 11 bllity Weight Polnt,C.. I cent) LDro,

1 v o H or 0 H 01 mgJk g.

11 c1 1 199.10 145-1455 cimuNo-Hcin; 59.15 1.01' "17.75 50.21 0.99 17.68 250 H 1 c1 1 213.11 1416143 11H15N0-H0l.-.. 1 1 15.54 1 1 I 15.53 23 '200-240 H 01 1,2 227.73 121-124 C H NO-HCL." 15.62 15.53 54 132 n 01 1 241.15 'GraH No-HCL. 1 5458 0.54 14.67 54.04 8.17 14.80, 42 H 01 1,155.79 913. 86; V 13.90 42 44.2 H 01 1 255.19 13.86 13.53 54 02 11 1 c1, 1 289,30 12.24 12.26 61 30.5 p-OCH; (base) "1 207.27 C1: I(6.67) 34 142 10011, or 1 285.81 145-141 0511501011101-.. 12.41 12.43 59 1-0011. .01, 1 519.13 155-151 .c.1rr=.No,-Hc1 01.59 5.52 11.09; 51.19 590 11.22 58 21 p 19-011 1 15243.72 20115-210 Qu u PH L I lg-2g {o1 e1" 1 1 1290.24. 141-149 GnHquClNO-HGI. 1222 1 12I22 a0 m,p-OH' o1 1 251.14" 02-201 01111011051101..- 55.49 5. 9 13.65 55.41 101 14.19 1.0 p,-Br 1 c1 1 1 154.10 155-151" OnHioBrNO-HOI. 1 .52 10.05 p-Cl rrccoo 1,2 341. 19 114 115 o.ani5o1N0|..'--.;11111 1101101 .10 4. 15

solublhty solubl e in (1 water (2) alcohol.

Insoluble in water as the base.

1 Yield 01 base from the N-benz'yl compound. 1 Yield of base from the S-pyrrolidinone. 3 Nitrogen analysis. 11 1 After recrystallization from butanone the compound in v mice for acute toxicity wherein evaluation of the melted at 152-154 C. I. .0 LD s was made by the method of Litchfield and Wil- Analysis.--Calculatcd for C H No C, 64.55; H, ,coxon, J. Pharm. and Exptl.-Therap.96, 99(1949). The 7.68. Found: C, 64.45; H,7.8,1.', LD results, are set out in Table I above.

The hydrochloride salt was prepared by treating 9. Additionally; members of. this group of compounds butanone solution of the base with ethereal hydrogen were tested in vivo in dogs for activity as inhibiting or chloride. It was crystallizedfrom a butanone-rnethanol 5 blocking agents to the effect on blood pressure of acetyl mixture; M. P. 202-203 C.

Analysis. -'-Ca1culated .for C H NO -HClz C, 55.49; cording to the following method. H, 6.99; (31-, 13.65;.N, 5.3 9J Found: C, 55.47; H, 7.07; 1 Mongrel dogs of either se'xiver'e anesthetized by the Cl, 14.19; N, 5.35. intravenous injection of phenobarbital sodium (100 mg./kg.). Surgery was supported with intravenous Example 'b g z ig"zg fi pentobarbital sodium. -A*carotid artery was cannulated C and connected to a mercury manometer for recording In an apparatus consisting of a two liter three-neck blood pressure; va Pt'eifier. cannula was inserted into the round-bottom flask fitted with a mechanical stirrer, a tracheaandlconnectedtoaMareytambour fiorrecording dropping funnel and a calcium chloride protected con- 'respiratio1 1'; aztemorali vein was;exp scd; for' introduction choline, histamine phosphate and adrenalin chloride, ac-

a rate-which maintained-gentle reflux of the solution.

of all materials; and the urinary bladder was catheterized formeasuring urinary output. Blood pressure and respiration were recorded by ink-writing levers on a Gorrell and Gorrell kymograph operated at Speed P. Electrocardiograms were recorded on a Grasselectroencephalograph (Model III D). Blood pressure responses to acetyl choline chloride, adrenalin chloride and histamine phosphate were recorded initially and at various times throughout the study. One animal was used for each compound.

A typical experiment evaluating l-ethyl-3-phenyl-3- pyrrolidinol hydrochloride is set out below.

Pharmacology Experiment A.The compound (l-ethyl- 3-phenyl-3-pyrrolidinol hydrochloride) was dissolved in physiologic saline at a concentration of 100 mg./ml. One female dog (No. 917) weighing.6.3 kg. received intravenous injections of ,the material in doses of -l.(),

.10, 10, 20, 40 and 80 mg./kg. during a period of four and one-half .hours. Another female dog.(No. 971) weighing 7.1 kg. received doses of20, 40 and 100 mg./ kg. during a period of three and one-half hours.

Dog. N0. 917.Intravenous injections of-1-ethyl-3- phenyl-3-pyrrolidinol hydrochloride in doses of 1.0

through 40 mg./kg. produced a transitory fall in blood augmented and the QRS complex was slightly depressed after both 10 mg./kg. doses. These effects are sometimes observed in apparently normal animals. 7

The most significant action of 1-ethyl-3-phenyl-3-pyrrolidinol hydrochloride was found to be its effect on the blood pressure response to adrenalin. Following the 1.0 mg./kg. dose of 1-ethyl-3-phenyl 3-pyrrolidinol hydrochloride the pressor response to adrenalin was markedly antagonized. Higher doses of 10 mg./kg. almost completely blocked the pressor activity. Responses to adrenalin followed the 20 and mg./kg. doses of lethyl-' 3-phenyl-3-pyrrolidinol hydrochloride demonstrated a reversal in activity of the adrenalin. A dose of adrenalin which was ten times the standard dose of l-gamma/kg. was needed to reconvert adrenalin to its pressor activity. The fact that blockade ofthe pressor response to adrenalin could be overcome by increasing the dose of adrenalin suggests a competitive inhibition between l-ethyl-3-phenyl- 3-pyrrolidinol hydrochloride and adrenalin for the receptor mechanism. Increasing the dose of l-ethyl-3- phenyl3-pyrrolidinol hydrochloride to 40 mg./kg. reversed the pressor response to even the high dose of adrenalin (10 gamma/kg.).

Dog. No. 971.--This animal was used to determine whether the blood pressure reversal to adrenalin following injection of 1-ethyl-3-phenyl-3-pyrrolidinol hydrochloride, as observed in Dog. No. 917, could be reproduced. I

The results were essentially the same for both dogs. The blood pressure responses to acetyl choline and histamine were unchanged by administration of l-ethyl-3- phenyl-3-pyrrolidinol hydrochloride, and urine flow was within normal limits throughout the study. Electrocardiograms were not taken on this animal.

A dose of 20 mg./kg. of l-ethyl-3-phenyl-3-pyrrolidinol hydrochloride completely reversed the blood pressure response to adrenalin. Within one hourafter injection of 7 the 20 mg./kg.-dos e the response .to adrenalin was biphasic, the pressor phase being equally as great as the depressor phase. By two hours it had returned to its primary'pressor activity; however, it remained markedly antagonized overthat of the control adrenalin response. The administration of 40 mg./kg. of l-ethyl-3-phenyl 3- pyrrolidinol. hydrochloride caused amore pronounced reversal of adrenalin activity than did the lower dose of 20 m'gJkg. I 1

Thecompounds of the invention, while negative as to inhibition of the action of acetyl choline and histamine showed substantial activity in antagonism of adrenalin. Theactivity "of the compoundswith respect to their uses as adrenergic blocking agents showed that as little as' 1.0 rn g./kg. inhibited the pressor action of adrenalin 'tested against'the standard dosage of l gamma/kg. of

adrenalin. A marked depression or blocking of the action .of adrenalin occurred with several ofthe compounds such as 3-phenyl-3-py rrolidinol hydrochlorideand l-ethyl- 3-phenyl-3-pyrrolidinolhydrochloride.at the 10 ing/kg. level and a complete reversal of the pressor action of adrenalin occurred with several compoundssuchas. 1- methyl-3-phenyl-3-pyrrolidinol hydrochloride and l-b enzyl-3-phenyl-3-pyrrolidinol hydrochloride at the 20-25 mg./kg. level. In some cases the duration of the blocking action or depressor action against adrenalin extended over a considerable length of time, approaching two hours following dosages of 10-20 mg./kg. This occurred in the use of compounds such as 3-phenyl-3-pyrrolidinol hydrochloride and 1-n-butyl-3-phenyl-3-pyrrolidinol hydrochloride. In other compounds such as 1-isobutyl-3- phenyl-3-pyrrolidinol hydrochloride the reversal of the pressor action of adrenalin even at higher dosages of the heterocyclic compound was slow in onset.

Generally, the 3-phenyl-3-pyrrolidinols showed greater activity as adrenergic blocking agents than the 3-p-alkoxyphenyl-3-pyrrolidinols. The compound 1-ethyl-3- (3,4,dihydroxyphenyl) 3 pyrrolidinol additionally has been found to have utility as an adrenergic agent similar to l-arterenol (Levophed).

The mechanism of action of the 3-aryl-3-pyrrolidinols is not known, but it would appear from the results that it may be a competitive action which selectively inhibits the response of ,efiector cells ordinarily stimulated by adrenalin.

For solubility reasons the hydrohalide salt form of the compounds is usually preferred and quaternary ammonium compounds are also operable. It is understood in. the following claims that pharmaceutically acceptable acid addition salts and quaternary compounds are equivalent to the free bases claimed. Various modifications may be made in the compounds of the present invention and it is to be understood that the invention is limited only by the scope of the appended claims.

Iclaim: l

. 3-phenyl-3-pyrrolidinol. .1-ethyl-3-phenyl-3-pyrrolidinol..

. l-n-butyl-3-phenyl-3-pyrrolidinol.

. 1-isobutyl-3'phenyl-3-pyrrolidinol.

. 1-benzyl-3-phenyl-3-pyrrolidinol. g g 1-ethyl-3-(3,4-dihydroxyphenyl)-3-pyrrolidinol.

. l-lower alkyl-3-phenyl-3-pyrrolidinol.

. 1-lower .alkyl-3-lower alkoxy phenyl-3-pyrrolidinol. 1-benzyl-3-methoxy phenyl-3-pyrrolidinol. 7

10. A compound of the group consisting of 3 -pheny1- 3-pyrrolidinols of the following formula:

9 10 wherein R is selected fiom the group consisting of hydro- 11. l-lower a1ky1-3-hydroxyphenyl-3-pyrrolidinol. gen, hydroxy, lower alkoxy, halogen and 3,4 dihydroxy; R is selected from the group consisting of hydrogen, References Cited inflle file of this Pawnt benzyl and lower alkyl and therapeutically acceptable acid h i k; J Am Chem Soc VOL 75 addition salts thereof. 5 5667-71 (1954). 

10. A COMPOUND OF THE GROUP CONSISTING OF 3-PHENYL3-PYRROLIDINOLS OF THE FOLLOWING FORMULA: 